Spodoptera Frugiperda

The insect cell baculovirus expression vector system (BEVS) is one of the most commonly used expression systems for recombinant protein production. This system is also widely used for the production of recombinant virus and virus-like particles. Although several published reports exist on recombinant protein expression using insect cells, information dealing with their metabolism in vitro is relatively scarce. In this work we have analyzed the metabolism of glucose and glutamine, the main carbon and/or energy compounds, of the two most commonly used insect cell lines, Spodoptera frugiperda (Sf-9) and the Trichoplusia ni BTI-Tn-5B1-4 (Tn-5). Radiolabeled substrates have been used to determine the flux of glucose carbon entering the tricarboxylic acid cycle (TCA) and the pentose phosphate (PP) pathway by direct measurement of 14 CO 2 produced. The percentage of total glucose metabolized to CO 2 via the TCA cycle was higher in the case of the Sf-9 (2.7%) compared to Tn-5 (0.6%) cells, while the percentage of glucose that is metabolized via the PP pathway was comparable at 14% and 16% for the two cell lines, respectively. For both cell lines, the remaining 83% of glucose is metabolized through other pathways generating, for example, lactate, alanine, etc. The percentage of glutamine oxidized in the TCA cycle was approximately 5-fold higher in the case of the Tn-5 (26.1%) as compared to the Sf-9 cells (4.6%). Furthermore, the changes in the metabolic fluxes of glucose and glutamine in Tn-5-PYC cells, which have been engineered to express a cytosolic pyruvate carboxylase, have been studied and compared to the unmodified cells Tn-5. As a result of this metabolic engineering, significant increase in the percentage of glucose oxidized in the TCA cycle (3.2%) as well as in the flux through the PP pathway (34%) of the Tn-5-PYC were observed.

This research aimed at studing Telenomus remus Nixon biology reared on Spodoptera frugiperda (J.E. Smith) eggs at different temperatures. Based on the development of the cycle (egg-adult), the thermal requirements and the number of parasitoid generations at constant temperatures were determined. Initially, 24-hour-old S. frugiperda eggs were submitted to parasitism by T. remus during 5 h, being then transferred to acclimatized chambers regulated at 15, 20, 25, 28, 31, and 35°C. The cycle (egg to adult) was influenced by temperature varying from 8.3±0.01 to 47.2±0.01 for females and 8.1±0.01 to 46.8±0.01 days for males at 31 and 15°C, respectively. The emergency (%) was also influenced by temperature. A reduction in emergency was observed at 15°C and no emergency at 35°C. T. remus sex ratio was not influenced by temperature. Sexual rate was not changed by temperature. Regarding to thermal requirements, thermal constant (K) and inferior thermal threshold (Tb) were higher for T. remus females (158.88 degree-days and 12.5°C) when compared to males (154.12 degree-days and 12.6°C). The estimated number of T. remus generation per year for males and females at laboratory conditions was 5.6 and 5.6, 16.9 and 17.3, 28.3 and 29.0, 35.1 and 36.0, 39.6 and 40.7 at 15, 20, 25, 28, and 31oC, respectively.

Neonicotinoid insecticides are compounds acting agonistically on insect nicotinic acetylcholine receptors (nAChR). They are especially active on hemipteran pest species such as aphids, whiteflies, and planthoppers, but also commercialized to control many coleopteran and some lepidopteran pest species. The most prominent member of this class of insecticides is imidacloprid. All neonicotinoid insecticides bind with high affinity (I 50 -values around 1 nM) to [ 3 H]imidacloprid binding sites on insect nAChRs. One notable ommission is the neonicotinoid thiamethoxam, showing binding affinities up to 10,000-fold less potent than the others, using housefly head membrane preparations. Electrophysiological whole cell voltage clamp studies using neurons isolated from Heliothis virescens ventral nerve cord showed no response to thiamethoxam when applied at concentrations of 0.3 mM, although the symptomology of poisoning in orally and topically treated noctuid larvae suggested strong neurotoxicity. Other neonicotinoids, such as clothianidin, exhibited high activity as agonists on isolated neurons at concentrations as low as 30 nM. There was no obvious correlation between biological efficacy of thiamethoxam against aphids and lepidopterans and receptor affinity in electrophysiological and binding assays. Pharmacokinetic studies using an LC-MS/MS approach to analyze haemolymph samples taken from lepidopteran larvae revealed that thiamethoxam orally applied to 5th instar Spodoptera frugiperda larvae was rapidly metabolized to clothianidin, an open-chain neonicotinoid. Clothianidin shows high affinity to nAChRs in both binding assays and whole cell voltage clamp studies. When applied to cotton plants, thiamethoxam was also quickly metabolized, with clothianidin being the predominant neonicotinoid in planta briefly after application, as indicated by LC-MS/MS analyses. Interestingly, the N-desmethylated derivative of thiamethoxam, N-desmethyl thiamethoxam, was not significantly produced in either lepidopteran larvae or in cotton plants, although it was often mentioned as a possible metabolite, being nearly as active as imidacloprid. In conclusion, our investigations show that thiamethoxam is likely to be a neonicotinoid precursor for clothianidin.

The fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is a harmful pest of many plants. In Egypt, the presence of S. frugiperda in maize fields was reported in 2019. The aim of this study was to record the parasitoids of S. frugiperda in Egypt. The survey was conducted at Sohag and Qena governorates. Survey studies showed five parasitoids were recorded. In Sohag governorate, from the total samples of fall armyworm collected, four species of parasitoids emerged, three of them belonged to order hymenoptera and one belonged to diptera. Two of the hymenopteran parasitoids were found in samples collected from Shandaweel district, Dinarmus basalis (Rondani, 1877) family Pteromalidae and Cotesia ruficrus (Haliday) family Braconidae. While the third is Microplitis rufiventris (Kokujev) family Braconidae was emerged from samples collected from El-Osyrat district. However, the dipteran parasitoid is Exorista (Tachina) larvarum (Linnaeus), which emerged from samples collected from Shandaweel district. In Qena governorate, one parasitoid species emerged Chelonus intermedius (Thomson) which was found in Abu Tesht district. Up to my knowledge this is the first record of the mentioned parasitoids on S. frugiperda in Egypt.

Spodoptera frugiperda is considered one of the main pest in corn and irrigated rice (fall armyworm) crops, causing high leaf losses. The objective of this study was to obtain an appropriate artificial diet to rear the biotypes "corn" and "rice" of S. frugiperda in laboratory. The insects were collected in areas cultivated with corn and irrigated rice in the meadow ecosystem and the identification was accomplished by the analysis of the DNA genomic. The development of the two biotypes was accompanied on Greene's diet and the same diet modified to 25 ± 1ºC, UR of 70 10% and fotofase of 14 hours. The study was accomplished with 150 larvae by diet individualized in glass tubes containing artificial diet. At emergency 20 couples were individualized and fed with aqueous solution of honey to 10%. The Greene diet made possible better development of the two biotypes, providing larger development speed, larger weight of larvae in the maximum development, weight of pupas and total fecundity, besides higher values of the net reproductive rates, intrinsic and finite rates of increase.

Fall armyworm is an invasive insect pest on maize which is causing huge loss to maize cultivators in Northern Karnataka. The field survey conducted in these areas during kharif 2018 indicated that the entomopathogenic fungi, Nomuraea rileyi is natural occurring on Spodoptera frugiperda with its infection ranging from 1.87 percent in Vijaypur to 18.30 percent in Dharwad district while, the percent damage of fall armyworm on maize ranged between 12.42 in Uttar Kannada and 65.73 percent in Dharwad district. Further, three large scale field evaluation studies conducted on this pathogen against the fall armyworm in maize revealed 58.91 to 62.87 percent reduction of pest infestation in these localities. Similarly, the larval and leaf injury reduction after 15 days of spraying N. rileyi ranged from 62.50 to 66.46 and 66.84 to 73.05 percent, respectively. The studies indicated the high potentiality of N. rileyi in combating the notorious invasive pest, S. frugiperda. This is the first report from India with respect to efficacy of N. rileyi against S. frugiperda under field conditions.

The fall armyworm (FAW) (Spodoptera frugiperda) is a crop pest species that has become global, having spread from its native American distribution to Africa and Asia since 2016. Its rapid spread, plus concerns about potential yield losses, have led to the search for sustainable management options. While most farmers affected by FAW in America have large-scale farm operations, the overwhelming majority of farmers in Africa and Asia are smallholders. This dramatically different context means that different management approaches must be sought. Large-scale producers with high-productivity, access to international market prices, risk-transfer mechanisms and the benefits of government subsidies are able to use technologies unavailable to smallholder farmers without access to those conditions. This review examines these differences and surveys the literature for accessible management options for smallholders, largely based on locally available solutions using ecological knowledge. Innovative digital solutions may also play a role in helping farmers learn about these solutions, and share them locally.

Fall armyworm larvae, Spodoptera frugiperda (J. E. Smith), were collected from sweet corn plants (Zea mays L.) in fields located in three south Florida counties. Fields were sampled from 2010 to 2015 during the fall and spring seasons. Larvae were transferred to the laboratory to complete development. The objective of the study was to identify the common parasitoids emerging from larvae that are present in sweet corn habitats where insecticides are traditionally used. A total of 8353 fall armyworm larvae were collected, of which 60.6% (5062) developed into moths after feeding on corn tissue and artificial diet. Parasitoids emerged from 2365 larvae (28.3%), and parasitism ranged from 1% to 91.7%, depending on site. Parasitism was higher at the University of Florida Everglades Research and Education (EREC) in Belle Glade (50.4 ± 11.8%) than at other locations in south Florida. Parasitism was comparable between fall and spring seasons, but was much higher in unsprayed fields (44.0 ± 9.6%) than in the sprayed fields (15.0 ± 2.5%). The two most common parasitoids that emerged from larvae were the solitary endoparasitoids Cotesia marginiventris (Cresson), found in 23 of the 25 sites sampled, and Chelonus insularis Cresson, found in 18 of the 25 sites sampled. Other parasitoid species that emerged from fall armyworm larvae were Aleiodes laphygmae (Viereck), Euplectrus platyhypenae Howard, Meteorus spp., Ophion flavidus Brullé, and unidentified species of Tachinidae. Techniques to improve the management of fall armyworm in overwintering areas of south Florida using conservation biological control are discussed.

The main insect pest in Brazilian corn is fall armyworm, Spodoptera frugiperda (Smith, 1797) (Lepidoptera: Noctuidae). Entomopathogenic nematodes (EPNs) can be used to control this pest, and can be applied together with various insecticides. Thus, the objective of this work was to evaluate the efficacy of mixtures of EPNs and insecticides to control S. frugiperda in corn crops. In laboratory bioassays three species of EPNs were tested (Heterorhabditis indica, Steinernema carpocapsae and Steinernema glaseri) together with 18 registered insecticides to control S. frugiperda in corn. Efficacy of association between insecticides and EPNs on S. frugiperda larvae was evaluated against the insect's third instar, 2 and 4 days after applications in laboratory. Experiments in the field were performed in two consecutive years, with located application of H. indica and S. carpocapsae (250 IJs/cm 2 ) mixed with chlorpyrifos (0.3 L/ha) and lufenuron (0.15 L/ha) on the corn husk. In laboratory, after two days exposure the interaction between chlorpyrifos and H. indica was synergistic, while interaction with cypermethrin, spinosad, methoxyfenozide and deltamethrin þ triazofos was additive, as was interaction between lufenuron, chlorpyrifos and cypermethrin with S. carpocapsae. In contrast, the interaction between chlorpyrifos (VexterÔ and LorsbanÔ) and lufenuron with S. glaseri was synergistic. In the field, the best treatment was the mixture of H. indica with lufenuron (0.15 L/ha), with 62.5% and 57.5% larval mortality in the two evaluation years in the field, respectively.

Spodoptera frugiperda is a polyphagous lepidopteran pest that encounters a wide range of toxic plant metabolites in its diet. The ability of this insect to adapt to its chemical environment might be explained by the action of major detoxification enzymes such as cytochrome P450s (or CYP). Forty-two sequences coding for P450s were identified and most of the transcripts were found to be expressed in the midgut, Malpighian tubules and fat body of S. frugiperda larvae. Relatively few P450s were expressed in the established cell line Sf9. In order to gain information on how these genes respond to different chemical compounds, larvae and Sf9 cells were exposed to plant secondary metabolites (indole, indole-3-carbinol, quercetin, 2-tridecanone and xanthotoxin), insecticides (deltamethrin, fipronil, methoprene, methoxyfenozide) or model inducers (clofibrate and phenobarbital). Several genes were induced by plant chemicals such as P450s from the 6B, 321A and 9A subfamilies. Only a few genes responded to insecticides, belonging principally to the CYP9A family. There was little overlap between the response in vivo measured in the midgut and the response in vitro in Sf9 cells. In addition, regulatory elements were detected in the promoter region of these genes. In conclusion, several P450s were identified that could potentially be involved in the adaptation of S. frugiperda to its chemical environment.

Dichloromethane extracts of Cedrela salvadorensis and Cedrela dugessi afforded a photogedunin epimeric mixture, gedunin and cedrelanolide. These compounds and the photogedunin epimeric acetates 3 and 4 at the 23-OH position were evaluated against Spodoptera frugiperda. Toosendanin, isolated from Melia azedarach, was used as a positive control. When tested for activity on neonate larvae into the no-choice bioassays, gedunin, photogedunin epimeric mixture, and photogedunin acetates mixture caused significant larval mortality with LC 50 of 39.0, 10.0, and 8.0 ppm at 7 days, respectively, as well as growth reduction. All the compounds tested inhibited larval growth, compared to the control, in a concentration-dependent manner. In addition, it was possible to observe significant reduced pupal weights and adult emergence. All the tested compounds except cedrelanolide showed comparable activity to that of toosendanin.

Plants respond to insect attack with the induction of volatiles that function as indirect plant defenses through the attraction of natural enemies to the herbivores. Despite the fact that volatiles are induced in response to caterpillar attack, their reciprocal effects on the host location behaviors of the same foraging herbivores are poorly understood. We examined orientation responses of sixth instar fall armyworm [FAW; Spodoptera frugiperda (Smith)] to odors from herbivore-damaged and undamaged maize seedlings (Zea mays var. Golden Queen) in y-tube olfactometer bioassays. While both damaged and undamaged maize seedlings were attractive compared with air, sixth instars preferred odors from damaged maize seedlings over odors from undamaged maize seedlings. Gas chromatography–mass spectrometry analysis of plant volatiles revealed that linalool and 4,8-dimethyl-1,3,7-nonatriene were the major volatiles induced by FAW herbivory 6 hr after initial damage. Given its prominence in induced plants and established attractiveness to adult FAW, linalool was evaluated both as an individual attractant and as a supplemental component of whole plant odors. Volatile linalool was more attractive than air to sixth instar FAW over a broad range of release rates. FAW also responded selectively to different amounts of linalool, preferring the higher amount. The orientation preferences of FAW were readily manipulated through capillary release of linalool into the airstream of whole plant odors. FAW preferred linalool over undamaged plant odors, and linalool-supplemented plant odors over unsupplemented plant odors, indicating that olfactory preferences could be changed by alteration of a single volatile component. These results suggest that although many induced volatiles attract natural enemies of herbivores, these defenses may also inadvertently recruit more larval herbivores to an attacked plant or neighboring conspecifics.

The generalist moth, Spodoptera frugiperda (J. E.
Smith) consists of two genetic subgroups (host strains) that
differ in their distribution among host plant species. The
corn strain prefers crop plants such as corn, sorghum, and
cotton, while the rice strain is found in small grasses such as
Cynodon spp. and rice. Little is known about the physiological
factors that drive this host preference. Here, we report a
feeding study with natural host plants and an artificial diet
containing cyanide. We found that corn, two Cynodon spp.
(bermudagrass C. dactylon (L.) Persoon, ‘NuMex Sahara’,
and stargrass C. nlemfuensis var. nlemfuensis Vanderyst,
‘Florona’), and a hybrid between bermudagrass and stargrass,
‘Tifton 85’, exhibited differences in the concentration
of the cyanogenic precursors or cyanogenic potential
(HCNp) and the release of hydrogen cyanide per unit time
or cyanogenic capacity (HCNc). Corn plants released low
levels of hydrogen cyanide, while stargrass had greater
HCNp/HCNc than bermudagrass and ‘Tifton 85’. Feeding
studies showed that corn strain larvae experienced higher
mortality than the rice strain when fed stargrass or artificial
diet supplemented with cyanide. Also, corn strain
larvae excreted higher levels of cyanogenic compounds
than the rice strain when fed Cynodon spp. These differences
in excretion suggest potential disparities in cyanide
metabolism between the two strains. We hypothesize that
differences in the susceptibility to cyanide levels in various
host plants could play a role in driving strain divergence
and what appears to be the incipient speciation of
this moth.

This work studied the parasitism capacity of Telenomus remus Nixon (Hymenoptera: Scelionidae) on Spodoptera frugiperda (Smith) (Hymenoptera: Scelionidae) eggs at 15, 20, 25, 28, 31, and 35°C, aiming to use this natural enemy in biological control programs in crops where S. frugiperda was considered pest. The parasitism during the first 24 h was 60.90, 81.65, 121.05, 117.55 and 108.55 parasited eggs per female from egg masses of approximately 150 eggs, at 15, 20, 25, 28 and 31°C, respectively. Females of T. remus reached parasitism higher than 80% at 15, 20, 25, 28 and 31ºC at 5, 27, 8, 2, and 2 days, respectively. At 35ºC, there was no parasitism. The highest parasitism rates occurred at 20, 25, 28 and 31°C. T. remus female longevity varied from 15.7 to 7.7 days from 15 to 31°C. The highest tested temperature (35°C) was inappropriate for T. remus development. At that temperature, female longevity was greatly reduced (1.7±0.02) and egg viability was null. All T. remus survival curves were of type I, which showed an increase in mortality rate with time.

In host range tests, O. antiqua SNPV was not infectious to 23 lepidopteran species representing four families. Heterologous Orgyia NPV isolates were permissive in O. antiqua larvae. Using a diet plug bioassay method, the median lethal dose response (LD 50 ) for this virus in second and third instar O. antiqua larvae were estimated at 52 and 539 PIBs per larva, respectively. 1999

An isolate of the Spodoptera frugiperda multiple nucleopolyhedrovirus comprises a stable proportion of deletion genotypes (e.g., SfNIC-C), that lack pif1 and pif2 rendering them noninfectious per os, and that survive by complementation with a complete genotype (SfNIC-B) in coinfected cells. To determine whether selection for particular ratios of complete and deletion genotypes occurs mainly during the establishment of the primary infection in insect midgut cells or during subsequent systemic infection, we examined genotype frequencies in insects that fed on OBs comprising different co-occluded mixtures of genotypes. Dramatic changes in genotype frequencies were observed between the OB inoculum and budded virus (BV) samples taken from larvae inoculated with OBs comprising 10% SfNIC-B + 90% SfNIC-C indicating that a marked reduction of SfNIC-C genotype had occurred in the insect midgut due to the immediate elimination of all OBs that originated from cells that had been infected only by SfNIC-C. In contrast, immediate changes were not observed in OBs comprising mixtures of 50% SfNIC-B + 50% SfNIC-C or those comprising 10% SfNIC-B + 90% SfNIC-C as most of the OBs in these mixtures originated from cells that had been infected by both genotypes. Subsequent changes in genotypic frequencies during five days of systemic infection were fairly small in magnitude for all genotypic mixtures. We conclude that the prevalence of defective genotypes in the SfNIC population is likely determined by a balance between host selection against OBs produced in cells infected by SfNIC-C alone and within-host selection for fast-replicating deletion genotypes. The strength of intra-host selection is likely modulated by changes in MOI during the infection period.

The main insect pest in Brazilian corn is fall armyworm, Spodoptera frugiperda (Smith, 1797) (Lepidoptera: Noctuidae). Entomopathogenic nematodes (EPNs) can be used to control this pest, and can be applied together with various insecticides. Thus, the objective of this work was to evaluate the efficacy of mixtures of EPNs and insecticides to control S. frugiperda in corn crops. In laboratory bioassays three species of EPNs were tested (Heterorhabditis indica, Steinernema carpocapsae and Steinernema glaseri) together with 18 registered insecticides to control S. frugiperda in corn. Efficacy of association between insecticides and EPNs on S. frugiperda larvae was evaluated against the insect's third instar, 2 and 4 days after applications in laboratory. Experiments in the field were performed in two consecutive years, with located application of H. indica and S. carpocapsae (250 IJs/cm 2 ) mixed with chlorpyrifos (0.3 L/ha) and lufenuron (0.15 L/ha) on the corn husk. In laboratory, after two days exposure the interaction between chlorpyrifos and H. indica was synergistic, while interaction with cypermethrin, spinosad, methoxyfenozide and deltamethrin þ triazofos was additive, as was interaction between lufenuron, chlorpyrifos and cypermethrin with S. carpocapsae. In contrast, the interaction between chlorpyrifos (VexterÔ and LorsbanÔ) and lufenuron with S. glaseri was synergistic. In the field, the best treatment was the mixture of H. indica with lufenuron (0.15 L/ha), with 62.5% and 57.5% larval mortality in the two evaluation years in the field, respectively.

The toxicity of a collection of 1400 isolates of Bacillus thuringiensis was assessed against the Lepidoptera Spodoptera frugiperda, Anticarsia gemmantalis and Plutella xylostella. Twenty seven isolates showed toxicity to the larvae of these insects with three isolates demonstrating significantly greater potency than the standard strain against Lepidoptera, B. thuringiensis serovar kurstaki HD1. These isolates were all found to produce bipyramidal crystals and major spore-associated protein bands of approximately 130 and 65 kDa, consistent with the detection of at least one cry1 and one cry2 family gene in each. The high level of insecticidal activity of these isolates makes them excellent candidates for further development for use in the field.

We assessed in the laboratory the attraction of the parasitoid Cotesia marginiventris (Cresson) toward odors emitted by conventional maize (Zea mays L. ssp. mays) and Bt (Bacillus thuringiensis) maize seedlings following actual or simulated injury by Spodoptera frugiperda (Smith), the parasitoid’s host, and emitted by the host’s frass, produced following consumption of conventional or Bt maize seedlings. Females of C. marginiventris exhibited similarly strong responses to conventional and Bt maize seedlings injured by the host or with simulated injury, and these were stronger than responses to clean air. In contrast, the responses of C. marginiventris females were consistently weaker toward host frass derived from Bt maize tissue compared to frass derived from conventional maize tissue. We hypothesized that the weakened response was due to a detrimental effect of Bt endotoxins, present in the Bt maize tissue, on the bacterial community present in the host’s gut and frass, including bacteria that produce odors attractive to C. marginiventris. As an initial test of our hypothesis, we compared between the responses of C. marginiventris females to host frass produced following consumption of Bt maize and frass produced from conventional maize which had been treated with an antibiotic (tetracycline) to eliminate host gut bacteria. Our results showed that C. marginiventris females responded similarly weakly to host frass derived from conventional maize tissue treated with antibiotic and to frass derived from Bt maize tissue, treated or untreated with antibiotic, while they responded strongly to frass derived from conventional maize untreated with antibiotic, so provided initial, partial support for our hypothesis. We discussed the weakened response of C. marginiventris females to host frass derived from Bt maize in the context of plausible impacts of transgenic crop cultivars on parasitoid foraging and populations, and the implications for biological control of non-target, polyphagous pests, such as S. frugiperda.

1H/15N and 13C NMR were used to investigate metabolism in Spodoptera frugiperda (Sf9) cells. Labelled substrates ([2-15N]glutamine, [5-15N]glutamine, [2-15N]glutamate, 15NH4Cl, [2-15N]alanine, and [1-13C]glucose) were added to batch cultures and the concentration of labelled excreted metabolites (alanine, NH4+, glutamine, glycerol, and lactate) were quantified. Cultures with excess glucose and glutamine produce alanine as the main metabolic by-product while no ammonium ions are released. 1H/15N NMR data showed that both the amide and amine-nitrogen of glutamine was incorporated into alanine in these cultures. The amide-nitrogen of glutamine was not transferred to the amine-position in glutamate (for further transamination to alanine) via free NH4+ but directly via an azaserine inhibitable amido-transfer reaction. In glutamine-free media 15NH4+ was consumed and incorporated into alanine. 15NH4+ was also incorporated into the amide-position of glutamine synthesised by the cells. These data suggest that the nitrogen assimilation system, glutamine synthetase/glutamate synthase (NADH-GOGAT), is active in glutamine-deprived cells. In cultures devoid of glucose, ammonium is the main metabolic by-product while no alanine is formed. The ammonium ions stem both from the amide and amine-nitrogen of glutamine, most likely via glutaminase and glutamate dehydrogenase. 13C NMR revealed that the [1-13C] label from glucose appeared in glycerol, alanine, lactate, and in extracellular glutamine. Labelling data also showed that intermediates of the tricarboxylic acid cycle were recycled to glycolysis and that carbon sources, other than glucose-derived acetylCoA, entered the cycle. Furthermore, Sf9 cell cultures excreted significant amounts glycerol (1.9-3.2 mM) and ethanol (6 mM), thus highlighting the importance of sinks for reducing equivalents in maintaining the cytosolic redox balance.

Pearl millet [Pennisetum glaucum (L.) R. Br.] is an alternative drought-tolerant grain crop for dryland summer production. Few insecticides are registered for use and insect management has not been extensively studied in pearl millet for grain production. Eleven trails were conducted during 2002-2004 in central and southern Georgia to understand the relative importance of insect pests and to evaluate the efficacy of currently registered insecticides against key pests. The main defoliator species were the fall armyworm [Spodoptera frugiperda (J.E. Smith)] and striped grassworm (Mocis latipes Guenée). Main insects feeding on grain heads were the corn earworm (Helicoverpa zea Boddie), sorghum webworm, (Nola sorghiella Riley), and stink bugs — brown stink bug (Euschistus spp.) and southern green stink bug [Nezara viridula (L.)]. All insects were effectively controlled by cypermethrin at 0.025 lb a.i./acre. The 0.015-lb a.i. rate was effective against sorghum webworm, striped grassworm, ...

The fall armyworm (Spodoptera frugiperda) is one of the most important pests of maize, causing up to 20% production losses when defoliation occurs near to flowering, or even complete destruction of plants. Among the alternatives to control this pest, the use of Bacillus thuringiensis (Bt) has gained attention due to its efficiency and low impact on natural enemies.

Insect cell lines from Arthropoda represented by Lepidoptera, Coleoptera, Diptera, and Homoptera were evaluated for their ability to support replication of AcMNPV. In addition, some of the cell lines that were refractive to AcMNPV were tested with AcMNPV hsp70 Red, a recombinant carrying the red fluorescent protein (RFP) gene, for their ability to express this protein after inoculation. Of the 10 lepidopteran cell lines tested, only three cell lines from Helicoverpa zea (BCIRL-HZ-AM1), Lymantria dispar (IPLB-LD 65), and Cydia pomonella (CP-169) failed to support detectable viral replication as measured by tissue culture infectious dose 50 (TCID:~) assay. Heliothis virescens (BCIRL-HV-AM1) produced the highest viral titer of 2.3 • 0.1 • 107 TCIDso/ml followed by Heliothis subflexa (BCIRL-HS-AM1) at 4.7 • 0.1 • 10 ~ TCIDffml and Spodopterafrugiperda (IPLB-SF21)at 4.1 • 0.1 • 106 TCIDso/ml. None of the coleopteran, dipteran, or homopteran cell lines supported AcMNPV replication. However, when studies were performed using AcMNPV hsp70 Red, the dipteran cell lines Aedes aegypti (ATC-10) and Drosophila melanogaster (line 2), both expressed the RFP as well as the refractive lepidopteran cell lines from H. zea and L. dispar. No RFP expression was observed in any of the coleopteran or homopteran cell lines. Cell lines refractive to AcMNPV did not appear to be adversely affected by the virus, as judged by their ability to multiply, nor was there any indication of induced apoptosis, as assessed by deoxyribonucleic acid fragmentation profiles or cell blebbing, or both.

The cry2Aa and cry2Ab genes from a Brazilian Bacillus thuringiensis strain were introduced into the genome of the baculovirus Autographa californica multiple nucleopolyhedrovirus (AcMNPV) in order to evaluate the heterologous proteins expression in insect cells and their toxicity to different insects. The recombinant viruses (vAcCry2Aa and vSynCry2Ab) were amplified in Trichoplusia ni (BTI-Tn5B1-4) cells and used to infect Spodoptera frugiperda larvae. Total extracts from S. frugiperda infected with the recombinant viruses were analysed by SDS-PAGE, which detected the presence of polypeptides around 65 kDa. Cuboid-shaped protein crystals were observed in insect extracts by light and scanning electron microscopy. Bioassays, using the heterologous proteins showed toxicity against second instar A. gemmatalis larvae (Cry2Aa) with a LC 50 of 1.03 lg/ml and second instar S. frugiperda larvae (Cry2Ab) with a LC 50 of 3.45 lg/ml. No toxic activity was detected for Aedes aegypti and Culex quinquenfaciatus.

The incidence of cannibalism of larval Spodoptera frugiperda (Lepidoptera: Noctuidae) on maize under field conditions was investigated using field cages. Cannibalism was found to account for approximately 40% mortality when maize plants were infested with two or four fourth-instar larvae over a 3-day period. Field trials examined the effect of larval density on the prevalence of natural enemies of S. frugiperda. The abundance of predators (earwigs, staphylinids, other predatory beetles, and Chrysoperla spp.) was significantly greater on maize plants with higher levels of larval feeding damage, while the relationship between predator abundance and number of S. frugiperda larvae per plant was less clear. As larval damage is probably a more reliable indicator of previous larval density than numbers collected at an evaluation, this indicates that predation risk will be greater for larvae living in large groups. Parasitism accounted for 7.1% mortality of larvae in sorghum, and involved six species of Hymenoptera and Tachinidae. There was no effect of larval density or within-plant distribution on the probability of larval attack by parasito-ids. The selective benefits of cannibalism, in relation to the risk of predation and parasitism, are discussed.

Laboratory studies were performed on the lethal and sublethal effects of spinosad on three important species of parasitoids attacking Spodoptera frugiperda (J.E. Smith) in Mexico. Reproduction of the braconid Chelonus insularis (Cresson), on treated egg masses was completely eliminated at 200 parts per million (ppm) and reduced by Â/70% at 20 ppm compared to the controls. Adult C. insularis did not avoid contact with residues on maize (200 ppm), but suffered a 7-day reduction in longevity after contact with residues. Initial toxicity of spinosad applied to a natural host of S. frugiperda was concentration dependent and resulted in 23 to 100% mortality of the eulophid Euplectrus plathypenae Howard at 25 to 200 ppm, respectively. The survival of Eu. plathypenae was initially reduced, especially in males, following contact with field weathered residues on maize (200 ppm). However, survival of both sexes rapidly returned to control values on foliage sampled after rainfall. A similar effect was observed in the mortality response of female Eu. plathypenae exposed to residues on sorghum. The ichneumonid Eiphosoma vitticolle Cresson did not avoid reproduction in S. frugiperda larvae that were externally contaminated with 200 ppm spinosad, although all spinosad-treated hosts died before the parasitoid progeny could develop. We use these results to predict the impact of spinosad applications on the foraging and reproduction of these parasitoids in the field. Such predictions require validation by field studies.

The objective of this work was to evaluate the effect of the temperature on the biology of the biotypes "corn" and "rice" of Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae) and to estimate the number of generations per year in laboratory and field. Caterpillars of four populations of S. frugiperda were collected in Rio Grande do Sul State, Brazil, identified by electrophoresis as the biotypes "corn" and "rice" in isolated areas (spaced for more than 300 km), areas of corn and irrigated rice production, as well as in adjacent areas that produces corn and rice irrigated side by side. The most appropriate temperature for the development of the two biotypes was 25ºC. In laboratory, a number between 11.0 and 11.3 generations year-1 for the biotype "corn" can be obtained, originating from isolated and adjacent areas, respectively, and, for the biotype "rice", 12.1 and 12.2 generations year-1 when originating from isolated and adjacent areas, respectively. In the field, the occurrence of 8.3 and 6.1 generations year-1 for the biotype "corn" was estimated, respectively, in isolated and adjacent areas and 8.4 and 7.0 generations year-1 for the "rice" biotype, respectively, in isolated and adjacent areas. In adjacent areas, the "rice" biotype presents an extra generation per year in relation to the "corn" biotype.

Adoption of integrated pest management (IPM) practices in the Guatemalan highlands has been limited by the failure of researchers and extensionists to promote genuine farmer participation in their efforts. Some attempts have been made to redress this failure in the diffusion-adoption process, but farmers are still largely excluded from the research process. Understanding farmers' agricultural knowledge must be an early step toward a more participatory research process. With this in mind, we conducted a semi-structured survey of 75 Cakchiquel Maya farmers in Patzún, Guatemala, to begin documenting their pest control practices. Their responses revealed that their understanding of biological and curative pest control is limited. However, their broad knowledge of cultural preventive pest control practices could explain why they had faced few pest problems in their traditional milpa (intercrop of corn, beans, and other edible plants). The majority of these preventive practices are probably efficient and environmentally innocuous.

androsaemum, Nerium oleander, Prunus laurocerasus, Aconitum nasutum, Laurus nobilis, Rhododendron caucasicum, Olea europaea, Punica granatum ve Daphne glomera bitkilerinden elde edilen özütlerin Autographa californica nüklear polihedrozis virüs (AcNPV, Baculovirus)'ün replikasyonlarına etkileri, virüslerin konsantrasyonu yönünden incelendi. U. duoica, H. androsaemum, L. nobilis, A. nasutum ve R. caucasicum bitki özütlerinin, virüs replikasyonunu azaltıcı bir etki meydana getirdiği gözlendi. N. oleander, P. laurocerasus, P. granatum, O. europaea ve D. glomera bitki özütlerinin ise virüs replikasyonunu arttırdıkları tespit edildi. Anahtar Kelimeler : Bitki özütü, baculovirus, antiviral THE EFFECT OF SOME PLANT EXTRACTS ON THE REPLICATION OF AUTOGRAPHA CALIFORNICA NUCLEAR POLYHEDROSIS VIRUS İN SPODOPTERA FRUGIPERDA CELL CULTURE ABSTRACT in this study, the effects of the crude extracts, obtained from Urtica dioica, Hypericum androsaemum, Nerium oleander, Prunus laurocerasus, Aconitum nasutum, Laurus nobilis, Rhododendron caucasicum, Olea europaea, Punica granatum and

A Nicaraguan field isolate (SfNIC) of Spodoptera frugiperda nucleopolyhedrovirus was purified by plaque assay on Sf9 cells. Nine distinct genotypes, A to I, were identified by their restriction endonuclease profiles. Variant SfNIC-B was selected as the standard because its restriction profile corresponded to that of the wild-type isolate. Physical maps were generated for each of the variants. The differences between variants and the SfNIC-B standard were confined to the region between map units 9 and 32.5. This region included PstI-G, PstI-F, PstI-L, PstI-K and EcoRI-L fragments. Eight genotypes presented a deletion in their genome compared with SfNIC-B. Occlusion body-derived virions of SfNIC-C, -D and -G accounted for 41% of plaque-purified clones. These variants were not infectious per os but retained infectivity by injection into S. frugiperda larvae. Median 50% lethal concentration values for the other cloned genotypes were significantly higher than that of the wild type. The variants also differed in their speed of kill. Noninfectious variants SfNIC-C and -D lacked the pif and pif-2 genes. Infectivity was restored to these variants by plasmid rescue with a plasmid comprising both pif and pif-2. Transcription of an SfNIC-G gene was detected by reverse transcription-PCR in insects, but no fatal disease developed. Transcription was not detected in SfNIC-C or -D-inoculated larvae. We conclude that the SfNIC population presents high levels of genetic diversity, localized to a 17-kb region containing pif and pif-2, and that interactions among complete and deleted genotypic variants will likely influence the capacity of this virus to control insect pests.

We investigated the consequences of cannibalism for some correlates of fitness in the fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae). The benefits gained by cannibals were ascertained by comparing survival, development rate, and pupal weight of larvae that had the opportunity to cannibalize with those that did not, at two levels of food availability. Larvae in the cannibalism treatments were provided with a conspecific one instar younger than themselves on five dates throughout larval development. Cannibalism was frequent; given the opportunity all larvae predated at least one younger conspecific. The frequency of cannibalism was not affected by the sex of the cannibal or by the availability of alternative food. However, cannibals suffered a significant reduction in survival at both high and low food availability. Furthermore, cannibals had a lower pupal weight in the high food treatment and a reduced development rate in the low food treatment. The only detectable fitness benefit associated with cannibalism was a positive correlation between the number of victims consumed and development rate under conditions of low food availability. On balance, cannibalism appears to be costly; alternative explanations for its occurrence in this species are discussed.

were performed to determine the efÞcacy of maize ßour-based granular formulations with ultralow rates of the naturally derived insecticide spinosad (0.1, 0.3, and 1.0 g [AI]/ha), for control of Spodoptera frugiperda (J.E. Smith) in maize, Zea mays L., in southern Mexico. Spinosad formulations were compared with a chemical standard, a commercial granular formulation of chlorpyrifos (150 g [AI]/ha). In both years, application of spinosad resulted in excellent levels of control, indicated by the number of living S. frugiperda larvae recovered from experimental plots. The efÞcacy of spinosad applied at 0.3 and 1.0 g (AI)/ha was very similar to that of chlorpyrifos. Natural reinfestation caused S. frugiperda numbers in insecticide treated plots to return to values similar to the control treatment by 10 Ð15 d postapplication. Many spinosad-intoxicated larvae collected in the Þeld died later in the laboratory in 2002, but not in 2003. Percentage mortality due to parasitoid emergence did not differ in any treatment in either Þeld trial. The number of parasitoids that emerged from S. frugiperda collected in each treatment was signiÞcantly reduced after application of spinosad (all rates) or chlorpyrifos due to a reduction in the number of host larvae. Parasitoid numbers returned to control values by 9 Ð15 d postapplication in all treatments. The most prevalent parasitoid was the braconid Chelonus insularis Cresson, which represented Ϸ80% of emerging parasitoids in both years. We conclude that appropriate formulation technology can greatly enhance the performance of this naturally derived, biorational insecticide.

\Ret'eired l4 Ottoht,r 2()l{); [inol rer.sion rectivt:d 2l Dacantbcr 20]l) The *rll tnly\\'onll. Spodoptcra./rugipertla (Sniith) (Leprcloptera: Noctuidae), is a major pest ol-maize ancl f recprently clenlrnds control rrea.sures. Tl-re tin-ring of rnsecticide aplrliclttion is a key Iactor it.t deterr.ttining its eliie iencl , so ar.t experiment rvas designed to investigirl.e this. Applcation ol'insecl.icide rvas basetl on three criteria: (i) lhe number o1' trap-caught moths in a Delta-type trap u,ilh a commercial sex pheromone lLrre placecl in tire center ol'the tafget. area, soou aliel plirnt emergence: (ii) the percentage o1'plants exhibiring pinhole-t-vpe dalrage (1091, or l0%) and (iii) the percentage oi'plauts erhibrting shot irole-t1,pe clamage (109i, or 209i,) con-rparecl to a sl'leck plot without any oontrol measures. We lbr.rnd that. the nunber clllrirp-caught moths rvas, conparetl t.o the other methocls, the besl nteans of deciding on insecticiclc rtpplication in nririzc to contlr)i tlrc fall arnrywolnr. L)sing phelontone trilps, we obraincd the bcst pcrfblrnance of thc insectrcirie Spinosarl. causing >900/u lalval moltality. Without insectrciclc;rppilcation. nraize yield reduction drLer to lall armj-\/ornr larva damage was 391/o. Kc'vwords: chemlcal conlrol; lir11 arm1,-worrnl integrated pest managerrlenl; pheromoue trapping {\el<l; Zcu ntoys Ittterno/ iortnl,lournal tt-f Pt:.tl M anagemertl Vol.58, No. l, J:rnuary*Nlarc'h 20t:.83-90

Purgative convolvulaceous resin glycosides are a family of amphipatic polysaccharides exhibiting potent, broad-spectrum of bactericidal and cytotoxic activities. In an attempt to unravel the mechanism of action of this class of biodynamic compounds, we studied the interaction of selected members from the tricolorin series, major constituents of Ipomoea tricolor, with Spodoptera frugiperda Sf9 insect cells. A membrane potential-sensitive fluorescent dye was used to monitor the time course and dosis-response effects of the test compounds on the permeability of the plasma membrane. All evaluated tricolorins with intact macrolactone-type structure and OH groups showed the ability to increase the membrane permeability to both cations (K + and Na + ) and anions (Cl − ) at a dose dependent fashion without any measurable delay, suggesting the formation of pores by these amphipatic molecules. These resin glycosides are active components of the biochemical arsenal employed by the morning glory species to kill target cells by permeabilizing their membranes to provoke an imbalance in cellular homeostasis.

Brush borders (microvilli) were isolated from Spodoptera frugiperda posterior midgut cells by using the cation differential precipitation technique. These microvilli preparations still contained some cytoskeleton elements visible by electron microscope. These elements are removed by Tris treatment followed by dilution and ultracentrifugation. Tris treatment solubilizes protein with M r values similar to some cytoskeleton proteins, and causes an increase in the specific activity of the marker enzyme (aminopeptidase) and in the lipid-protein ratio of the purified microvillar membrane. Microvilli preparations from anterior midgut cells seem to be free from cytoskeleton. This is supported by electron microscopy and by the absence, after Tris treatment, of changes in the specific activity of the marker enzyme and in the lipid-protein ratio. The cytoskeleton of these microvilli should assemble and disassemble to permit the passage of vesicles observed migrating through them. As a result, it is likely that the cytoskeleton is not rigid and is lost during microvilli preparation by differential precipitation. In comparison with other insects, S. frugiperda purified microvillar membranes have low cholesterol, carbohydrate and lipid-protein ratios. Because S. frugiperda midgut microvillar membranes almost lack intrinsic digestive enzymes, their low lipid-protein ratios might result from a large amount of carrier or other proteins.

A L-glycosidase (M r 50 000) from Spodoptera frugiperda larval midgut was purified, cloned and sequenced. It is active on aryl and alkyl L-glucosides and cellodextrins that are all hydrolyzed at the same active site, as inferred from experiments of competition between substrates. Enzyme activity is dependent on two ionizable groups (pK a1 = 4.9 and pK a2 = 7.5). Effect of pH on carbodiimide inactivation indicates that the pK a 7.5 group is a carboxyl. k cat and K m values were obtained for different p-nitrophenyl L-glycosides and K i values were determined for a range of alkyl L-glucosides and cellodextrins, revealing that the aglycone site has three subsites. Binding data, sequence alignments and literature L-glycosidase 3D data supported the following conclusions: (1) the groups involved in catalysis were E 187 (proton donor) and E 399 (nucleophile) ; (2) the glycone moiety is stabilized in the transition state by a hydrophobic region around the C-6 hydroxyl and by hydrogen bonds with the other equatorial hydroxyls; (3) the aglycone site is a cleft made up of hydrophobic amino acids with a polar amino acid only at its first (+1) subsite. ß 0167-4838 / 01 / $^see front matter ß 2001 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 7 -4 8 3 8 ( 0 0 ) 0 0 2 6 0 -0 Abbreviations: M r , relative molecular

Na concepção de manejo integrado, a meta não se trata de exterminar a praga, mas de manter sua população regulada, reduzindo-a a um limite compatível com a produção econômica da cultura e a conseqüente manutenção da qualidade ambiental (Cruz 1995). Logo, deve-se sempre ter atenção aos fatores de supressão e regulação de populações, avaliando-se as densidades populacionais da praga e de seus inimigos naturais.